This invention relates, in general, to 90 degree hybrids, and more specifically, to quadrature hybrids.
Major components in many microwave systems are hybrids. Hybrids and couplers used in MMIC (monolithic microwave integrated circuit) designs generally require quarter wave distributed elements that are too large for frequencies below 10 Ghz. Branch line hybrids can be simulated using lumped elements instead of quarter wave distributed elements, but the simulated hybrids are subject to substantial losses, and operate within a narrow bandwidth (.apprxeq.5%). Furthermore, the lumped elements get large as the frequency of operation decreases. Therefore, conventional MMIC circuits require off chip 90 degree hybrid functions.